US girl, 9, and her twin brothers, 6, struck by car while boarding school bus

Three siblings from Indiana in the US were fatally hit by a passing truck as they crossed the road to board their school bus on Tuesday morning.

Mentone Elementary School students Alivia Stahl, nine, and Xzavier and Mason Ingle, both six, were on their way to school when the incident occurred.

The bus, which had pulled up on the other side of the two-lane road, had put its hazard lights on and provided a stop sign to indicate for oncoming traffic to stop.

"It’s a very delicate situation. Just a very, very sad situation," Police Sergeant Tony Slocum said, according to People. "It’s a very hard scene. I haven’t seen troopers cry in a long time."

"The father had to come out and identify his children, it was excruciating," he added.

A fourth child, 11-year-old Maverik Lowe, was also struck by the 2017 Toyota Tacoma and remains in critical condition.

"He has multiple broken bones. My last report was that he was conscious so that’s a good thing," Slocum said.

The driver, 24-year-old Alyssa Shepherd, is currently in custody. She has been charged with three counts of reckless homicide and one count of ignoring a stop sign and causing injury, according to ABC News.

At the time of the accident, there were no other passengers on the bus.